1. Field of the Invention
This invention relates to a tire valve and low pressure indicator. More specifically, this invention relates to an integral tire valve and low pressure indicator of the type disclosed and claimed in the application of Harry C. Winther, U.S. Ser. No. 182,606 filed Aug. 29, 1980, now abandoned.
The earlier valve and indicator comprises a tubular body adapted to be mounted in a rim-hole opening in an automobile wheel, for instance. The end of the body inside the tire is formed with a seat, and a valve poppet engages against the seat. A spring within the tubular body urges the poppet away from the seat and an indicator piston is disposed in the tubular body above the poppet. When the tire pressure falls, the spring overcomes the pressure within the tire and drives the poppet open permitting air from the tire to enter the tubular body and force the indicator piston into signalling position. The unit is more thoroughly disclosed, of course, in the aforementioned application. A special advantage of the unit is that the indicator feature does not interfere with the normal functions of gauging, filling and venting characteristic of the normal tire valve.
The present invention enhances the reliability of the Winther-type tire valve and low pressure indicator.
2. Description of the Prior Art
The closest prior art of the present invention is the aforementioned Winther tire valve and low pressure indicator.
Aside from the Winther device the patent art discloses a number of "add-on" indicators adapted to be threaded on to a standard tire valve and a number of elaborate signalling means, some of which involve signals on the dashboard within the vehicle. It will suffice to note that Winther is by far the most pertinent art.
While the valve of the aforementioned application is in every way meritorious, one of the design mandates for its proper functioning is that the wall surrounding the poppet be very close to assure the proper piston action of the air in the tire against the poppet once the filling chuck is removed after filling. Such piston action is necessary to effect the seating of the poppet. Without seating, the valve is non-functional. This design mandate is in practice translated into a manufacturing requirement that is onerous in terms of strict adherence to very close predetermined tolerances with consequent expense in the form of time taken in constant dimension checking and in the form of excessive rejection of product.